It has been proposed to provide tape for digitally encoded television signals in cassettes of different dimensions; the widths dimension of the tape is governed by the recording apparatus and will stay the same. The plan dimension of the cassettes, however, will change in accordance with the storage capacity of reels in the cassettes. While the width is standardized, three plan dimensions for respectively small or S, medium or M, and large or L reels and hence cassettes have been proposed. For example, sizes, in plan view, of the cassettes which would meet these requirements have been suggested of 172.times.109 mm for a S-cassette, 254.times.150 mm for the M-cassette and 366.times.206 mm for the L-cassettes.
Smallest size of the cassettes can be obtained by placing the respective cassette reels as close to each other as possible. This means that a tape cassette having only a short tape length wound thereon can be constructed such that the axes of rotation of the tape reels are closer to each other than in a cassette of medium, or large tape reserve. For universal applicability of a transducer apparatus, however, it is desirable that the transducer apparatus can operate with any cassette of the set, in which the set is defined by the width of the tape being standard, and the dimensions of the S, M and L-cassettes, or other cassettes being variable. Such sets are particularly suitable for digital TV recording in studios, to permit programs of respectively different lengths to be recorded and reproduced from their own tapes in their own cassettes.
The magnetic tape transport function requires that the respective tape reels are either driven, or braked, or retarded, in accordance with a predetermined transport direction and transport conditions. For defined engagement with the magnetic tape reels in the cassettes, a fixed connection between the reel drive shafts, or drive connections and the reels themselves is necessary. Thus, if the various cassettes of a set have different spacing of the reels from each other, it is necessary that the shafts of the dynamo electric apparatus, such as winding motors, or dynamic brakes, can be placed at different spacing from each other, to match the spacing of the reels in the respectively different cassettes.
Eurpopean patent disclosure document 0 133 822 Shiratori describes a magnetic tape apparatus for recording or reproduction of recorded contents which permits matching of different axial spacing of the tape reels of cassettes by providing a pair of movable reel tables, for example for engagement with the cassette reels. The reel tables are directly supported on shafts of the dynamo electric apparatus, which are movable in a common plane on guide tracks, in mirror image with respect to each other. The guide tracks are angled with respect to each other by 90.degree.. Upon simultaneous shift of the motors, including the reel tables, the axial spacing of the reel tables will change in the desired manner. The drive of the shift arrangement is obtained by crank and worm gear couplings, together with a directing linkage, coupled to the worm gear couplings. The cranks are operated in respectively opposite direction. Linear relationship between the angular paths of the worms and reel tables via the worm gears is not, however, obtained and the linear path of the shift and the reel tables and reels coupled thereto cannot be reliably maintained. Only at the end positions of the cranks are definite relationships between the cranks and the shifting mechanism, typically a carriage or the like possible, that is, the absolute position of the shafts rotating the respective reels on the shift plane.